The document discusses tensile testing and the properties that can be determined from a tensile test. It explains that a tensile test involves clamping a sample between grips and applying a load while measuring elongation. The stress-strain curve obtained provides important mechanical properties like elastic limit, yield strength, and tensile strength. Yield strength indicates the stress at which permanent deformation begins, while tensile strength is the maximum stress withstood before failure. The test determines how a material responds to applied forces and is important for material selection and design.
The document discusses the iron-carbon phase diagram and the microstructures that form in steels of different carbon compositions. It defines the key phases - ferrite, austenite, cementite, pearlite - and explains how they form and transform based on the iron-carbon diagram. Specifically, it describes how hypoeutectoid, eutectoid, and hypereutectoid steels will transform as they cool, forming either primary ferrite, pearlite, or primary cementite structures respectively. The document provides detailed information on interpreting the iron-carbon phase diagram.
The document discusses the iron-carbon equilibrium diagram, which shows the different crystal structures of iron alloys at various temperatures and carbon concentrations. It defines the ferrite, austenite, and cementite phases and explains how their proportions change with cooling in hypoeutectoid, eutectoid, and hypereutectoid steel compositions. The key phase changes of peritectic, eutectic, and eutectoid reactions are also summarized along with how the diagram is used to understand the microstructures and properties of steels and cast irons.
1. The document discusses the iron-carbon equilibrium diagram, which shows the different phases of iron as carbon content and temperature vary.
2. It describes the different phases of iron - ferrite, austenite, cementite - and how their crystal structures and carbon solubility change with temperature.
3. Pearlite, an important microstructure in steel, is a lamellar structure composed of alternating layers of ferrite and cementite that forms during a eutectoid reaction when austenite cools below 723°C.
The document discusses the iron-carbon phase diagram, which shows the different crystal structures that iron takes on at various temperatures depending on the amount of carbon present. It defines various phases including austenite, ferrite, cementite, pearlite, and martensite, and explains how heating and cooling rates affect the microstructure. Heat treatments like tempering, annealing, and normalizing are also summarized in terms of their effects on the steel microstructure.
The document discusses the iron-carbon phase diagram, which maps the equilibrium phases present in iron-carbon alloys at different temperatures and carbon concentrations. It defines various phases including ferrite, austenite, cementite, pearlite, and martensite. The diagram shows three important reactions - the peritectic, eutectic, and eutectoid reactions. It explains how the microstructure of hypoeutectoid, eutectoid, and hypereutectoid steels changes during cooling based on their carbon content. The phase diagram is important for understanding heat treatments of steels and how carbon concentration affects the mechanical properties of different steel grades.
The document discusses the iron-carbon phase diagram and the microstructures of plain carbon steels. It begins by explaining the different phases in the Fe-C system, including ferrite, austenite, cementite, and their crystal structures. It then describes how to properly draw the iron-carbon phase diagram, labeling important curves, temperatures, and carbon percentages. Finally, it illustrates the microstructures that form upon cooling for hypoeutectoid, eutectoid, and hypereutectoid plain carbon steels, such as proeutectoid ferrite, pearlite, and proeutectoid cementite.
Iron iron carbide equilibrium phase dia gramGulfam Hussain
The document provides information about the iron-iron carbide phase diagram, including:
1) It shows the different phases that appear on the diagram (austenite, ferrite, pearlite, cementite, etc.) and the transformations between them like the eutectic and eutectoid reactions.
2) It explains how the microstructure of steels and cast irons depends on the cooling process and carbon content, resulting in structures like pearlite, ferrite, or cementite.
3) It describes how alloying elements can change the eutectoid composition and temperature, allowing the properties of steels to be tailored for different applications.
The document discusses the iron-carbon phase diagram, which maps the different crystal structures that iron alloys adopt at various temperatures and carbon concentrations. It defines various structures including ferrite, austenite, cementite, pearlite, and martensite. The diagram shows three important reaction lines - the peritectic, eutectic, and eutectoid reactions. It explains how the microstructure of steels with different carbon levels transforms during heating and cooling, resulting in different microstructures like pearlite or ferrite/cementite mixtures. The phase diagram is important for understanding the properties of steels and their heat treatment.
The document discusses the iron-carbon phase diagram and the microstructures that form in steels of different carbon compositions. It defines the key phases - ferrite, austenite, cementite, pearlite - and explains how they form and transform based on the iron-carbon diagram. Specifically, it describes how hypoeutectoid, eutectoid, and hypereutectoid steels will transform as they cool, forming either primary ferrite, pearlite, or primary cementite structures respectively. The document provides detailed information on interpreting the iron-carbon phase diagram.
The document discusses the iron-carbon equilibrium diagram, which shows the different crystal structures of iron alloys at various temperatures and carbon concentrations. It defines the ferrite, austenite, and cementite phases and explains how their proportions change with cooling in hypoeutectoid, eutectoid, and hypereutectoid steel compositions. The key phase changes of peritectic, eutectic, and eutectoid reactions are also summarized along with how the diagram is used to understand the microstructures and properties of steels and cast irons.
1. The document discusses the iron-carbon equilibrium diagram, which shows the different phases of iron as carbon content and temperature vary.
2. It describes the different phases of iron - ferrite, austenite, cementite - and how their crystal structures and carbon solubility change with temperature.
3. Pearlite, an important microstructure in steel, is a lamellar structure composed of alternating layers of ferrite and cementite that forms during a eutectoid reaction when austenite cools below 723°C.
The document discusses the iron-carbon phase diagram, which shows the different crystal structures that iron takes on at various temperatures depending on the amount of carbon present. It defines various phases including austenite, ferrite, cementite, pearlite, and martensite, and explains how heating and cooling rates affect the microstructure. Heat treatments like tempering, annealing, and normalizing are also summarized in terms of their effects on the steel microstructure.
The document discusses the iron-carbon phase diagram, which maps the equilibrium phases present in iron-carbon alloys at different temperatures and carbon concentrations. It defines various phases including ferrite, austenite, cementite, pearlite, and martensite. The diagram shows three important reactions - the peritectic, eutectic, and eutectoid reactions. It explains how the microstructure of hypoeutectoid, eutectoid, and hypereutectoid steels changes during cooling based on their carbon content. The phase diagram is important for understanding heat treatments of steels and how carbon concentration affects the mechanical properties of different steel grades.
The document discusses the iron-carbon phase diagram and the microstructures of plain carbon steels. It begins by explaining the different phases in the Fe-C system, including ferrite, austenite, cementite, and their crystal structures. It then describes how to properly draw the iron-carbon phase diagram, labeling important curves, temperatures, and carbon percentages. Finally, it illustrates the microstructures that form upon cooling for hypoeutectoid, eutectoid, and hypereutectoid plain carbon steels, such as proeutectoid ferrite, pearlite, and proeutectoid cementite.
Iron iron carbide equilibrium phase dia gramGulfam Hussain
The document provides information about the iron-iron carbide phase diagram, including:
1) It shows the different phases that appear on the diagram (austenite, ferrite, pearlite, cementite, etc.) and the transformations between them like the eutectic and eutectoid reactions.
2) It explains how the microstructure of steels and cast irons depends on the cooling process and carbon content, resulting in structures like pearlite, ferrite, or cementite.
3) It describes how alloying elements can change the eutectoid composition and temperature, allowing the properties of steels to be tailored for different applications.
The document discusses the iron-carbon phase diagram, which maps the different crystal structures that iron alloys adopt at various temperatures and carbon concentrations. It defines various structures including ferrite, austenite, cementite, pearlite, and martensite. The diagram shows three important reaction lines - the peritectic, eutectic, and eutectoid reactions. It explains how the microstructure of steels with different carbon levels transforms during heating and cooling, resulting in different microstructures like pearlite or ferrite/cementite mixtures. The phase diagram is important for understanding the properties of steels and their heat treatment.
The document introduces various steels and the steelmaking process. It discusses how pig iron is produced in a blast furnace and its composition. Steel is an iron alloy with up to 1.5% carbon and other elements that gives a wide range of strengths. The steelmaking process oxidizes carbon in pig iron and modern processes use oxygen. Ladle metallurgy is used to further refine steel. Steel can be cast, rolled, or delivered in other forms for different applications.
In their simplest form, steels are alloys of Iron (Fe) and Carbon (C). The Fe-C phase diagram is a fairly complex one, but we will only consider the steel and cast iron part of the diagram, up to 6.67% Carbon
This document provides information about the iron-carbon phase diagram and the microstructures that form in steels based on their carbon content and heat treatments. It discusses the various phases in the Fe-C system including ferrite, austenite, cementite, and martensite. It also summarizes how heating and cooling rates can affect phase transformations through phenomena like supercooling and influence the resulting microstructures like pearlite, bainite, and spheroidite. The mechanical properties of different microstructures are also addressed, with martensite described as the hardest and most brittle.
The document discusses the iron-carbon phase diagram. It describes three important reactions:
1) The eutectic reaction occurs at 4.3% carbon and 1,147°C, where liquid transforms to austenite and cementite.
2) The eutectoid reaction occurs at 0.76% carbon and 727°C, where austenite transforms to ferrite and cementite to form pearlite.
3) The peritectic reaction occurs at 0.16% carbon and 1,493°C, where liquid and delta-ferrite transform to austenite.
The phase diagram is used to explain the microstructures that form in steels with different carbon
This document defines and describes the various phases that appear on the iron-carbon phase diagram. It defines ferrite, austenite, pearlite, cementite, martensite, and ledeburite. It describes their crystal structures, carbon content, properties, and how they form during heating and cooling processes. The key reactions on the iron-carbon phase diagram are the peritectic reaction at 1490°C, the eutectic reaction at 1130°C, and the eutectoid reaction at 723°C. The transformation of austenite to ferrite and cementite upon cooling is also explained for hypo-eutectoid, eutectoid, and hyper-
The document summarizes key concepts about the iron-carbon phase diagram and microstructures in steels. It describes the various phases in the Fe-Fe3C system, including α-ferrite, γ-austenite, δ-ferrite, and Fe3C cementite. It explains how the microstructure of steels, such as pearlite, depends on the carbon content and cooling rate. Phase transformations like the eutectoid reaction are also summarized.
The document describes the iron-carbon phase diagram. It discusses the solid phases in the diagram including ferrite, austenite, cementite, pearlite, and ledeburite. It also discusses the critical temperatures for phase changes during heating and cooling. These include the A0, A1, A2, A3, Acm, and A4 temperatures. Finally, it discusses the three invariant reactions that occur on the iron-carbon phase diagram: the peritectic reaction, eutectic reaction, and eutectoid reaction.
The document discusses the iron-iron carbide phase diagram and the microstructural changes that occur in steels of different carbon compositions during heating and cooling. It outlines the phases present - ferrite, austenite, cementite - and their structures. Steels are defined as solid solutions of carbon in iron, with classifications based on carbon content: low carbon <0.2%, medium 0.2-0.4%, and high carbon >0.4%. The diagram shows eutectic, peritectic, and eutectoid reactions that occur, and how the microstructures of eutectoid, hypoeutectoid, and hypereutectoid steels change during cooling.
The iron-carbon diagram (also called the iron-carbon phase or equilibrium diagram) is a graphic representation of the respective microstructure states depending on temperature (y axis) and carbon content (x axis).
The document describes the iron-iron carbide phase diagram. It shows the different phases that appear with increasing carbon percentage, including ferrite, austenite, pearlite, cementite, and martensite. The diagram indicates three important reactions - the peritectic reaction at 1490°C, the eutectic reaction at 1130°C, and the eutectoid reaction at 723°C. It explains how the microstructure of steels and cast irons depends on the cooling process relative to these phase changes and reactions.
This document discusses heat treatment of steel and the phases and reactions involved. It describes the peritectic, eutectic, and eutectoid reactions that occur during heating and cooling of steel. It also defines the different phases present like ferrite, austenite, cementite, and their crystal structures and magnetic properties. Additionally, it classifies steels based on their carbon content into low, medium, and high carbon varieties and provides examples of AISI numbering systems.
The document discusses heat treatment processes and the iron-carbon phase diagram. It describes the various phases in steel like ferrite, austenite, cementite and pearlite. The critical temperatures on the Fe-C diagram are defined, including eutectoid temperature A1 and eutectic temperature A4. Micrographs show the microstructures of allotriomorphic ferrite, pearlite and ledeburite. The objectives of heat treatment like increasing strength and improving properties are mentioned.
The document summarizes the iron-iron carbide phase diagram. It describes the various phases that appear on the diagram including ferrite, pearlite, austenite, cementite, and martensite. It also outlines the three invariant reactions - the peritectic, eutectic, and eutectoid reactions. Finally, it discusses how the phase diagram is used to understand the microstructural transformations in steels and cast irons that occur during heating and cooling.
This document summarizes Piyush Verma's presentation on the Fe-Fe3C phase diagram for plain carbon steel. It introduces the key phases in iron like ferrite, austenite, cementite and pearlite. It explains how carbon enters the iron crystal lattice and affects its properties. The phase diagram shows the different phases present at various temperatures and carbon concentrations. It also describes the mechanisms of phase transformations like reconstructive and displacive transformations during heating and cooling of steel.
Iron Iron-carbide Equilibrium Phase Dia GramGulfam Hussain
The document summarizes key concepts in the iron-iron carbide equilibrium diagram:
- It describes three horizontal lines on the diagram - the peritectic line at 1479°C, eutectic line at 1140°C, and eutectoid line at 723°C.
- It defines the peritectic, eutectic, and eutectoid reactions - where the peritectic forms austenite from liquid and solid, the eutectic forms austenite and cementite from liquid, and the eutectoid forms pearlite from austenite.
- It provides details on the phases austenite, ferrite
This document provides a case analysis of Airborne Express, a former cargo airline and express delivery company. It includes an introduction to the company's history and operations, as well as analyses of Porter's 5 Forces, Airborne's competitive strategies, its costs relative to FedEx, pricing approaches, and recommendations for strengthening its position. The document evaluates how industry structure has changed over time and the impact on attractiveness. It also analyzes Airborne's strategy of focusing on corporate clients, lower pricing, and metropolitan areas to differentiate itself from competitors.
The document introduces various steels and the steelmaking process. It discusses how pig iron is produced in a blast furnace and its composition. Steel is an iron alloy with up to 1.5% carbon and other elements that gives a wide range of strengths. The steelmaking process oxidizes carbon in pig iron and modern processes use oxygen. Ladle metallurgy is used to further refine steel. Steel can be cast, rolled, or delivered in other forms for different applications.
In their simplest form, steels are alloys of Iron (Fe) and Carbon (C). The Fe-C phase diagram is a fairly complex one, but we will only consider the steel and cast iron part of the diagram, up to 6.67% Carbon
This document provides information about the iron-carbon phase diagram and the microstructures that form in steels based on their carbon content and heat treatments. It discusses the various phases in the Fe-C system including ferrite, austenite, cementite, and martensite. It also summarizes how heating and cooling rates can affect phase transformations through phenomena like supercooling and influence the resulting microstructures like pearlite, bainite, and spheroidite. The mechanical properties of different microstructures are also addressed, with martensite described as the hardest and most brittle.
The document discusses the iron-carbon phase diagram. It describes three important reactions:
1) The eutectic reaction occurs at 4.3% carbon and 1,147°C, where liquid transforms to austenite and cementite.
2) The eutectoid reaction occurs at 0.76% carbon and 727°C, where austenite transforms to ferrite and cementite to form pearlite.
3) The peritectic reaction occurs at 0.16% carbon and 1,493°C, where liquid and delta-ferrite transform to austenite.
The phase diagram is used to explain the microstructures that form in steels with different carbon
This document defines and describes the various phases that appear on the iron-carbon phase diagram. It defines ferrite, austenite, pearlite, cementite, martensite, and ledeburite. It describes their crystal structures, carbon content, properties, and how they form during heating and cooling processes. The key reactions on the iron-carbon phase diagram are the peritectic reaction at 1490°C, the eutectic reaction at 1130°C, and the eutectoid reaction at 723°C. The transformation of austenite to ferrite and cementite upon cooling is also explained for hypo-eutectoid, eutectoid, and hyper-
The document summarizes key concepts about the iron-carbon phase diagram and microstructures in steels. It describes the various phases in the Fe-Fe3C system, including α-ferrite, γ-austenite, δ-ferrite, and Fe3C cementite. It explains how the microstructure of steels, such as pearlite, depends on the carbon content and cooling rate. Phase transformations like the eutectoid reaction are also summarized.
The document describes the iron-carbon phase diagram. It discusses the solid phases in the diagram including ferrite, austenite, cementite, pearlite, and ledeburite. It also discusses the critical temperatures for phase changes during heating and cooling. These include the A0, A1, A2, A3, Acm, and A4 temperatures. Finally, it discusses the three invariant reactions that occur on the iron-carbon phase diagram: the peritectic reaction, eutectic reaction, and eutectoid reaction.
The document discusses the iron-iron carbide phase diagram and the microstructural changes that occur in steels of different carbon compositions during heating and cooling. It outlines the phases present - ferrite, austenite, cementite - and their structures. Steels are defined as solid solutions of carbon in iron, with classifications based on carbon content: low carbon <0.2%, medium 0.2-0.4%, and high carbon >0.4%. The diagram shows eutectic, peritectic, and eutectoid reactions that occur, and how the microstructures of eutectoid, hypoeutectoid, and hypereutectoid steels change during cooling.
The iron-carbon diagram (also called the iron-carbon phase or equilibrium diagram) is a graphic representation of the respective microstructure states depending on temperature (y axis) and carbon content (x axis).
The document describes the iron-iron carbide phase diagram. It shows the different phases that appear with increasing carbon percentage, including ferrite, austenite, pearlite, cementite, and martensite. The diagram indicates three important reactions - the peritectic reaction at 1490°C, the eutectic reaction at 1130°C, and the eutectoid reaction at 723°C. It explains how the microstructure of steels and cast irons depends on the cooling process relative to these phase changes and reactions.
This document discusses heat treatment of steel and the phases and reactions involved. It describes the peritectic, eutectic, and eutectoid reactions that occur during heating and cooling of steel. It also defines the different phases present like ferrite, austenite, cementite, and their crystal structures and magnetic properties. Additionally, it classifies steels based on their carbon content into low, medium, and high carbon varieties and provides examples of AISI numbering systems.
The document discusses heat treatment processes and the iron-carbon phase diagram. It describes the various phases in steel like ferrite, austenite, cementite and pearlite. The critical temperatures on the Fe-C diagram are defined, including eutectoid temperature A1 and eutectic temperature A4. Micrographs show the microstructures of allotriomorphic ferrite, pearlite and ledeburite. The objectives of heat treatment like increasing strength and improving properties are mentioned.
The document summarizes the iron-iron carbide phase diagram. It describes the various phases that appear on the diagram including ferrite, pearlite, austenite, cementite, and martensite. It also outlines the three invariant reactions - the peritectic, eutectic, and eutectoid reactions. Finally, it discusses how the phase diagram is used to understand the microstructural transformations in steels and cast irons that occur during heating and cooling.
This document summarizes Piyush Verma's presentation on the Fe-Fe3C phase diagram for plain carbon steel. It introduces the key phases in iron like ferrite, austenite, cementite and pearlite. It explains how carbon enters the iron crystal lattice and affects its properties. The phase diagram shows the different phases present at various temperatures and carbon concentrations. It also describes the mechanisms of phase transformations like reconstructive and displacive transformations during heating and cooling of steel.
Iron Iron-carbide Equilibrium Phase Dia GramGulfam Hussain
The document summarizes key concepts in the iron-iron carbide equilibrium diagram:
- It describes three horizontal lines on the diagram - the peritectic line at 1479°C, eutectic line at 1140°C, and eutectoid line at 723°C.
- It defines the peritectic, eutectic, and eutectoid reactions - where the peritectic forms austenite from liquid and solid, the eutectic forms austenite and cementite from liquid, and the eutectoid forms pearlite from austenite.
- It provides details on the phases austenite, ferrite
This document provides a case analysis of Airborne Express, a former cargo airline and express delivery company. It includes an introduction to the company's history and operations, as well as analyses of Porter's 5 Forces, Airborne's competitive strategies, its costs relative to FedEx, pricing approaches, and recommendations for strengthening its position. The document evaluates how industry structure has changed over time and the impact on attractiveness. It also analyzes Airborne's strategy of focusing on corporate clients, lower pricing, and metropolitan areas to differentiate itself from competitors.
یکی از هیجاناتی که انسانها از سالهای اولیه تولدان را تجربه میکنند خشم است هیجان خشم نیز مانند سایر هیجانات که در نهاد انسان وجود دارد برای رشد وبقای انسان لازم است .کودک در سالهای قبل از مدرسه از خشم بیشتر بهعنوان وسیلهای برای رسیدن به خواستههایش استفاده میکند وهروقت دررسیدن به آنچه میخواهد ناتوان باشد خشم را بروز میدهد و به شکل لگدزدن ،جیغ کشیدن و یا فریاد زدن انرا رها میکند اما در سنین بالاتر خشم کودک بیشتر حالت خصمانه پیدا میکند تا وسیلهای .
This document is a curriculum vitae for Nang Thw e Thw e Soe that includes personal details, education and qualifications, employment history, and other skills. Some key points:
- Nang Thw e Thw e Soe has over 10 years of experience in finance roles for international NGOs and organizations in Myanmar.
- She holds a Bachelor's degree in Economics from Meiktila Institute of Economics and various accounting qualifications.
- Her most recent role is as Grants Accountant at Plan International Myanmar since 2015, where she manages financial reporting for humanitarian projects funded by donors like UNICEF, WFP, and EU.
- Prior experience includes finance roles
This document provides information about purchasing a 3Com 15663 product from Launch 3 Telecom. It describes how to purchase the item via phone, email, or by submitting a request for quote online. It also provides details about payment methods, same-day shipping, warranty, and repair and other services offered by Launch 3 Telecom.
The document is a study guide for a chemistry exam covering various organic chemistry topics including allylic and conjugated systems, aromaticity, electrophilic aromatic substitution, carbonyl chemistry, amino acids, and peptide sequencing. It provides definitions, reaction mechanisms, and practice problems for students to review key concepts that will be tested like identifying hybridizations and drawing Frost diagrams for aromatic compounds, outlining the steps of electrophilic aromatic substitution and Friedel-Crafts reactions, interconverting functional groups like carbonyls, hemiacetals, and acetals, and sequencing peptides after cleavage by specific proteases. The study guide also offers general exam preparation advice and reminds students to trust their conceptual understanding of material to answer problems.
The document is a study guide for a chemistry exam covering various organic chemistry topics including allylic and conjugated systems, aromaticity, electrophilic aromatic substitution, carbonyl chemistry, amino acids, and peptide sequencing. It provides definitions, reaction mechanisms, and practice problems for key concepts that will be tested. The study guide emphasizes memorizing fundamental steps and rules for different reaction types as well as clearly indicating hybridizations and understanding how underlying concepts link various topics together. It concludes by recommending getting sufficient rest before the exam and trusting one's conceptual understanding of material to answer problems, even those involving unfamiliar reactions.
A learner profile describes how a student learns best through their skills, interests, barriers and recommendations for support. It includes information on a student's learning preferences, strengths, needs and past supports. A learner profile is dynamic and informs classroom practices like planning, layout and scheduling to enable student participation. They can be created by a student or with parents, and include things like interests, hopes, dislikes, support systems and examples of past supports. Developing a learner profile involves determining the learner's identity and goals, how they navigate education through their choices and independence, and how they demonstrate growth.
An editorial presents the opinion of a newspaper's editorial board on an issue. There are several types of editorials: those that provide information, interpret events, criticize problems/situations, commend individuals/organizations, argue a perspective to persuade readers, entertain readers while suggesting truth, present a philosophy rather than an argument, and explain the significance of special occasions.
This document summarizes key aspects of the iron-carbon phase diagram and phase transformations in steel alloys. It describes the different phases in the diagram including α-ferrite, γ-austenite, δ-ferrite, and Fe3C cementite. It also discusses how the microstructure of hypoeutectoid, eutectoid, and hypereutectoid steel compositions depends on cooling rate and the transformations of austenite to other phases. Finally, it introduces isothermal transformation diagrams that show how the rate of phase transformations varies with temperature over time.
This document provides information about the iron-carbon phase diagram and the microstructures that form in steels based on their carbon content and heat treatments. It discusses the various phases in the Fe-C system including ferrite, austenite, cementite, and martensite. It also summarizes how heating and cooling rates can affect phase transformations through phenomena like supercooling and influence the resulting microstructures like pearlite, bainite, and spheroidite. The mechanical properties of different microstructures are also addressed, with martensite described as the hardest and most brittle.
Part-2 Leaning to plot Fe-c diagram-BNB-audio.pptBiranchiBiswal3
The document provides information about the iron-iron carbide phase diagram, including:
1) It describes the three allotropic forms of iron that exist at atmospheric pressure - alpha iron, gamma iron, and delta iron.
2) It outlines the three horizontal lines on the phase diagram which indicate isothermal reactions - the peritectic reaction at 1490°C, the eutectic reaction at 1130°C, and the eutectoid reaction at 723°C.
3) It defines several important terms related to the phase diagram including steel, cast iron, pearlite, austenite, and ferrite as well as their properties.
This document provides information on the iron-carbon phase diagram and the microstructures that form in steels based on their carbon content and heat treatments. It discusses the various phases in the Fe-C system, including ferrite, austenite, cementite, and martensite. It also summarizes how heating and cooling rates can affect the formation of microstructures like pearlite, bainite, and spheroidite. The document outlines how properties vary based on the relative amounts and sizes of the different phases present in the microstructure.
The iron-carbon phase diagram shows the equilibrium phases that exist at different temperatures depending on the carbon content of the alloy. It includes the following phases:
1) Ferrite - a body-centered cubic phase stable at lower temperatures.
2) Austenite - a face-centered cubic phase stable at intermediate temperatures.
3) Cementite - an iron-carbon intermetallic compound.
4) Pearlite - a lamellar structure of ferrite and cementite that forms during slow cooling of eutectoid steel.
5) Martensite - a super-saturated solid solution of carbon in ferrite that forms during rapid quenching.
The document summarizes key aspects of the iron-iron carbide (Fe-Fe3C) phase diagram. It discusses the various phases present in the diagram, including α-ferrite, γ-austenite, δ-ferrite, cementite, and liquid iron-carbon solutions. The maximum solubility of carbon in each phase is specified. Microstructures that form via peritectic, eutectic, and eutectoid reactions are described. The development of microstructures for hypoeutectoid, eutectoid, and hypereutectoid steel compositions is explained. Methods for calculating phase fractions using lever rule are provided, along with example problems.
Heat treatment, phases, microstructures and its propertiesHitesh Basitti
The document discusses phases, microstructures, and properties in materials. It defines a phase as a region that differs in structure and/or composition from another region. It explains that phase diagrams provide information on the number and types of phases present at different temperatures and compositions, and can show equilibrium solid solubility and temperature ranges for phase changes. Gibb's phase rule relates the number of phases, components, and degrees of freedom in a system. Solid solutions are discussed as single-phase atomic mixtures, including substitutional and interstitial types. The iron-carbon phase diagram is examined in detail, outlining the different phases such as austenite, ferrite, cementite, and eutectic or peritectic
The document discusses the iron-carbon phase diagram, which maps the different crystal structures that form in iron-carbon alloys at various temperatures and carbon percentages. It defines various structures including ferrite, austenite, pearlite, and cementite. The phase diagram shows three main reactions - the peritectic, eutectic, and eutectoid reactions. Based on their carbon percentage, steels can form different microstructures like ferrite-pearlite or cementite-pearlite when cooled from austenite. The diagram is important for understanding steel heat treatments and tailoring mechanical properties.
This document provides an overview of material science and engineering concepts related to iron-carbon alloys, including:
- The iron-carbon phase diagram, which shows the different phases that form based on carbon content and temperature. Key phases discussed include austenite, ferrite, pearlite, and cementite.
- The TTT (time-temperature-transformation) diagram, which shows the decomposition of austenite under non-equilibrium conditions based on time and temperature.
- Common heat treatment processes for steels like annealing, hardening, tempering, and their purposes. Hardening involves rapid cooling to form martensite for hardness while tempering reduces brittleness.
The document discusses the iron-carbon phase diagram. It explains that the diagram shows the different phases that exist in iron-carbon alloys at various temperatures, including ferrite, austenite, cementite, pearlite, and martensite. The key phase transformations on the diagram are the peritectic reaction, eutectic reaction, and eutectoid reaction. The document summarizes how the microstructure of hypoeutectoid, eutectoid, and hypereutectoid steels changes during cooling based on their carbon content.
DJJ3213 MATERIAL SCIENCE CHAPTER 4 NOTE.pptfieyzaadn
The document discusses material science concepts related to solid solutions and phase diagrams. It begins by describing the stages of grain structure formation during solidification. It then differentiates between base metals and alloys, describing various types of solid solutions like disordered, ordered, and interstitial. Terminologies in phase diagrams are explained, including phases, equilibrium, composition, liquidus, and solidus temperatures. Binary alloy systems containing two components are discussed. Finally, the key aspects of the iron-carbon phase diagram are summarized, including the various phases like ferrite, austenite, cementite, pearlite, and martensite that form at different temperature ranges and carbon concentrations.
1) The document discusses the iron-iron carbide (Fe-Fe3C) phase diagram and the various phases present, including α-ferrite, γ-austenite, δ-ferrite, cementite, and liquid iron-carbon solutions.
2) It describes three invariant reactions on the phase diagram - the peritectic reaction, eutectic reaction, and eutectoid reaction - and explains how they influence the crystal structure changes with temperature and carbon concentration.
3) The document classifies ferrous alloys as iron, steel, or cast iron depending on their carbon concentration and discusses how their microstructure changes with cooling, such as the formation of pearlite and pro
The document provides information on heat treatment processes and the fundamentals of heat treatment of metals. It discusses the Fe-C equilibrium diagram and various phases in steel like ferrite, cementite, austenite, and pearlite. It describes the microstructure and properties of these phases. It also covers heat treatment processes like annealing, normalizing, hardening and discusses methods of surface hardening, heat treatment of cast irons and nonferrous metals. Various heat treatment parameters and objectives are defined. Diagrams of phase transformations and microstructures are included.
The iron-carbon phase diagram shows the equilibrium phases that exist at different temperatures for iron-carbon alloys. It includes three main phase transformations: the peritectic reaction where liquid transforms to austenite above 1400°C, the eutectic reaction where liquid transforms to austenite and cementite at 1130°C, and the eutectoid reaction where austenite transforms to ferrite and cementite at 723°C. The diagram is used to understand the microstructures that form during cooling of steels based on their carbon content, such as mixtures of ferrite and pearlite for eutectoid steels or ferrite/cementite for hypoeutect
Mumbai University.
Mechanical Engineering
SEM III
Material Technology
MOdule 2.2
Theory of Alloys& Alloys Diagrams :
Significance of alloying, Definition, Classification and properties of different types of alloys, Solidification of pure metal, Different types of phase diagrams (Isomorphous, Eutectic,
08
University of Mumbai, B. E. (Mechanical Engineering), Rev 2016 19
Peritectic, Eutectoid, Peritectoid) and their analysis, Importance of Iron as engineering material, Allotropic forms of Iron, Influence of carbon in Iron- Carbon alloying Iron-Iron carbide diagram and its analysis
The document discusses heat treatment processes and concepts. It defines heat treatment as operations involving heating, soaking, and cooling to achieve desired microstructures and properties. The major objectives of heat treatment are outlined, such as increasing strength and hardness. Key concepts discussed include the Fe-C phase diagram, phases such as ferrite, austenite, and cementite, and critical temperatures. Common heat treatment processes are also mentioned such as annealing, hardening, and tempering.
This document discusses the iron-carbon phase diagram and the various transformations that occur in iron-carbon alloys. It describes the different phases that exist - liquid, delta ferrite, austenite, alpha ferrite, and cementite. It explains the phase transformations that occur during solidification and cooling of iron-carbon alloys depending on their carbon content. These include peritectic, eutectic, and eutectoid transformations. It also discusses microstructures like pearlite and the effects of heat treatments.
Part a). Pearlite - Pearlite is a two-phased, lamellar (or l.pdfannaelctronics
>> Part a).
>> Pearlite :- Pearlite is a two-phased, lamellar (or layered) structure composed of alternating
layers of ferrite (88 wt%) and cementite (12 wt%) that occurs in some steels and cast irons. In
fact, the lamellar appearance is misleading since the individual lamellae within a colony are
connected in three dimensions; a single colony is therefore an interpenetrating bicrystal of ferrite
and cementite. In an iron-carbon alloy, during slow cooling pearlite forms by a eutectoid reaction
as austenite cools below 727 °C (1,341 °F) (the eutectoid temperature). Pearlite is a
microstructure occurring in many common grades of steels.
>> Cementite :- Cementite, also known as iron carbide, is an interstitial compound of iron and
carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By
weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard,
brittle material, normally classified as a ceramic in its pure form, though it is more important in
ferrous metallurgy. While iron carbide is present in most steels and cast irons, it is produced as a
raw material in the Iron Carbide process, which belongs to the family of alternative ironmaking
technologies.
>> Austenite :- Austenite, also known as gamma-phase iron (-Fe), is a metallic, non-magnetic
allotrope of iron or a solid solution of iron, with analloying element. In plain-carbon steel,
austenite exists above the critical eutectoid temperature of 1,000 K (1,340 °F; 730 °C); other
alloys of steel have different eutectoid temperatures. It is Face Centred Cubic Configuration
(FCC).
>> Eutectoid Phase :- When the solution above the transformation point is solid, rather than
liquid, an analogous eutectoid transformation can occur. For instance, in the iron-carbon system,
the austenite phase can undergo a eutectoidtransformation to produce ferrite and cementite, often
in lamellar structures such as pearlite and bainite.
>> Proeutectoid :- When a hot steel with carbon content very close to 0.8%, is cooled down
slowly, there is a temperature (723 deg C) at which a constant-temperature transformation takes
place. This is called eutectoid transformation. And this results in formation of alternate layers of
Ferrite and Iron-Carbide (Fe3C).
But if the carbon content in this hot steel is much less than 0.8%, and it is cooled down slowly,
then till the temperature reduces to 723 deg C, a part of Austenite (also called gamma iron) gets
transformed to Ferrite by rejecting carbon from the solution. This is not a constant-temperature
process and occurs over a range of temperature. The ferrite so formed is called Proeutectoid...At
723 deg C, all the remaining Austenite get converted to Pearlite at this constant temperature -
which is nothing but alternate layers of Ferrite and cementite
>> Martensite :- Martensite, most commonly refers to a very hard form of steel crystalline
structure, but it can also refer to any crystal structure that is form.
The document summarizes the iron-iron carbide phase diagram. It describes three key phase reactions - the peritectic reaction, eutectic reaction, and eutectoid reaction. It also defines the various structures that appear on the diagram, including ferrite, austenite, cementite, pearlite, and martensite. Additionally, it discusses how hypoeutectoid steels, hypereutectoid steels, and cast irons form based on their position on the diagram during cooling. The phase diagram is important for understanding the microstructure and properties of steels.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
ML Based Model for NIDS MSc Updated Presentation.v2.pptx
14691 a03e6 mse2
1. 1) Write Avrami rate equation in phase transformation.
The Avrami equation describes how solids transform from one phase (state of matter) to
another at constant temperature. It can specifically describe the kinetics of crystallisation., can be
applied generally to other changes of phase in materials, like chemical reaction rates, and can even
be meaningful in analyses of ecological systems.
2) List the different phases that exist in Fe-C equilibrium diagram.
shows the equilibrium diagram for combinations of carbon in a solid solution of iron. The
diagram shows iron and carbons combined to form Fe-Fe3C at the 6.67%C end of the diagram. The
left side of the diagram is pure iron combined with carbon, resulting in steel alloys. Three
significant regions can be made relative to the steel portion of the diagram. They are the eutectoid
E, the hypoeutectoid A, and the hypereutectoid B. The right side of the pure iron line is carbon in
combination with various forms of iron called alpha iron (ferrite), gamma iron (austenite), and
delta iron. The black dots mark clickable sections of the diagram.
Allotropic changes take place when there is a change in crystal lattice structure. From 2802º-2552ºF
the delta iron has a body-centered cubic lattice structure. At 2552ºF, the lattice changes from a
body-centered cubic to a face-centered cubic lattice type. At 1400ºF, the curve shows a plateau but
this does not signify an allotropic change. It is called the Curie temperature, where the metal
changes its magnetic properties.
Two very important phase changes take place at 0.83%C and at 4.3% C. At 0.83%C, the
transformation is eutectoid, called pearlite.
gamma (austenite) --> alpha + Fe3C (cementite)
At 4.3% C and 2066ºF, the transformation is eutectic, called ledeburite.
L(liquid) --> gamma (austenite) + Fe3C (cementite)
3.What is a fatigue fracture?
The majority of engineering failures are caused by fatigue. Fatigue failure is defined as the
tendency of a material to fracture by means of progressive brittle cracking under repeated
alternating or cyclic stresses of an intensity considerably below the normal strength. Although the
fracture is of a brittle type, it may take some time to propagate, depending on both the intensity and
frequency of the stress cycles.
4) What is a composite material?
A composite material (also called a composition material or shortened to composite) is a
material made from two or more constituent materials with significantly different physical or
chemical propertie that, when combined, produce a material with characteristics different from thes
2. individual components. The individual components remain separate and distinct within the finished
structure. The new material may be preferred for many reasons: common examples include
materials which are stronger, lighter, or less expensive when compared to traditional materials.
More recently, researchers have also begun to actively include sensing, actuation, computation and
communication into composites,which are known as robotic materials.
5) What are the coordinates of a phase diagram?
pressure (P) and temperature (T) are usually the coordinates. The phase diagrams usually
shows the (P, T) conditions for stable phases.
6.What is the abbreviation of TTT diagram?
Time temperature transformation
7.What is diffusion?
Diffusion is the net movement of molecules or atoms from a region of high concentration to a
region of low concentration
8.What is an interstitial impurity?
Small impurity interstitial atoms are usually on true off-lattice sites between the lattice atoms.
Such sites can be characterized by the symmetry of the interstitial atom position with respect to its
nearest lattice atoms
For instance, an impurity atom I with 4 nearest lattice atom A neighbours (at equal
distances) in a FCC lattice is in a tetrahedral symmetry position, and thus can be called a tetrahedral
interstitial.
9.What is a brittle facture?
Brittle fracture is the fracture of a metal or other material without appreciable prior plastic
deformation. It is a break in a brittle piece of metal which failed because stress exceeded cohesion.
Brittle fracture of normally ductile steels occurs primarily in large, continuous, box-like structures .
10. What is hardness?
Hardness is a measure of how resistant solid matter is to various kinds of permanent shape change
when a compressive force is applied. Some materials, such as metal, are harder than others.
Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior
of solid materials under force is complex; therefore, there are different measurements of hardness:
scratch hardness, indentation hardness, and rebound hardness.
11.Define ceramics.
A ceramic is an inorganic non-metallic solid made up of either metal or non-metal compounds
that have been shaped and then hardened by heating to high temperatures. In general, they are hard,
corrosion-resistant and brittle.
Ceramic comes from the Greek word meaning ‘pottery’. The clay-based domestic wares, art objects
3. and building products are familiar to us all, but pottery is just one part of the ceramic world.
12.How are polymers classified?
A))based on synthesis
B))based on inter molecular forces
C))from source
D))based on material
E))based on structure
*Draw and explain Fe-Fe3C phase diagram?
A study of the microstructure of all steels usually starts with the iron carbide . It provides an
invaluable foundation on which to build knowledge of both carbon steels and alloy steels, as well
as a number of various heat treatments they are usually subjected to (hardening, annealing, etc).
Figure 1. The Fe-Fe3C phase diagram shows which phases are to be expected at metastable
equilibrium for different combinations of carbon content and temperature. The metastable Fe-C
phase diagram was calculated with cal , coupled with PBIN thermodynamic database.
At the low-carbon end of the Fe-Fe3C phase diagram, we distinguish ferrite (alpha-iron), which
can at most dissolve 0.028 wt. % C at 738 °C, and austenite (gamma-iron), which can dissolve 2.08
wt. % C at 1154 °C. The much larger phase field of gamma-iron (austenite) compared with that of
4. alpha-iron (ferrite) indicates clearly the considerably grater solubility of carbon in gamma-iron
(austenite), the maximum value being 2.08 wt. % at 1154 °C. The hardening of carbon steels, as
well as many alloy steels, is based on this difference in the solubility of carbon in alpha-iron
(ferrite) and gamma-iron (austenite).
At the carbon-rich side of the metastable Fe-C phase diagram we find cementite (Fe3C). Of less
interest, except for highly alloyed steels, is the delta-ferrite at the highest temperatures.
The vast majority of steels rely on just two allotropes of iron: (1) alpha-iron, which is body-
centered cubic (BCC) ferrite, and (2) gamma-iron, which is face-centered cubic (FCC) austenite.
At ambient pressure, BCC ferrite is stable from all temperatures up to 912 °C (the A3 point), when
it transforms into FCC austenite. It reverts to ferrite at 1394 °C (the A4 point). This high-
temperature ferrite is labeled delta-iron, even though its crystal structure is identical to that of
alpha-ferrite. The delta-ferrite remains stable until it melts at 1538 °C.
Regions with mixtures of two phases (such as ferrite + cementite, austenite + cementite, and ferrite
+ austenite) are found between the single-phase fields. At the highest temperatures, the liquid phase
field can be found, and below this are the two-phase fields (liquid + austenite, liquid + cementite,
and liquid + delta-ferrite). In heat treating of steels, the liquid phase is always avoided.
The steel portion of the Fe-C phase diagram covers the range between 0 and 2.08 wt. % C. The cast
iron portion of the Fe-C phase diagram covers the range between 2.08 and 6.67 wt. % C.
The steel portion of the metastable Fe-C phase diagram can be subdivided into three regions:
hypoeutectoid (0 < wt. % C < 0.68 wt. %), eutectoid (C = 0.68 wt. %), and hypereutectoid (0.68
< wt. % C < 2.08 wt. %).
A very important phase change in the Fe-Fe3C phase diagram occurs at 0.68 wt. % C. The
transformation is eutectoid, and its product is called pearlite (ferrite + cementite):
gamma-iron (austenite) —> alpha-iron (ferrite) + Fe3C (cementite).
Some important boundaries at single-phase fields have been given special names. These include:
• A1 — The so-called eutectoid temperature, which is the minimum temperature for austenite.
• A3 — The lower-temperature boundary of the austenite region at low carbon contents; i.e., the
gamma / gamma + ferrite boundary.
• Acm — The counterpart boundary for high-carbon contents; i.e., the gamma / gamma + Fe3C
boundary.
Sometimes the letters c, e, or r are included:
5. • Accm — In hypereutectoid steel, the temperature at which the solution of cementite in austenite is
completed during heating.
• Ac1 — The temperature at which austenite begins to form during heating, with the c being derived
from the French chauffant.
• Ac3 — The temperature at which transformation of ferrite to austenite is completed during
heating.
• Aecm, Ae1, Ae3 — The temperatures of phase changes at equilibrium.
• Arcm — In hypereutectoid steel, the temperature at which precipitation of cementite starts during
cooling, with the r being derived from the French refroidissant.
• Ar1 — The temperature at which transformation of austenite to ferrite or to ferrite plus cementite
is completed during cooling.
• Ar3 — The temperature at which austenite begins to transform to ferrite during cooling.
• Ar4 — The temperature at which delta-ferrite transforms to austenite during cooling.
If alloying elements are added to an iron-carbon alloy (steel), the position of the A1, A3, and Acm
boundaries, as well as the eutectoid composition, are changed. In general, the austenite-stabilizing
elements (e.g., nickel, manganese, nitrogen, copper, etc) decrease the A1 temperature, whereas the
ferrite-stabilizing elements (e.g., chromium, silicon, aluminum, titanium, vanadium, niobium,
molybdenum, tungsten, etc) increase the A1 temperature.
The carbon content at which the minimum austenite temperature is attained is called the eutectoid
carbon content (0.68 wt. % C in case of the Fe-Fe3C phase diagram). The ferrite-cementite phase
mixture of this composition formed during slow cooling has a characteristic appearance and is
called pearlite and can be treated as a microstructural entity or microconstituent. It is an aggregate
of alternating ferrite and cementite lamellae that coarsens (or "spheroidizes") into cementite
particles dispersed within a ferrite matrix after extended holding at a temperature close to A1.
Finally, we have the martensite start temperature, Ms, and the martensite finish temperature,
Mf:
• Ms — The highest temperature at which transformation of austenite to martensite starts during
rapid cooling.
• Mf — The temperature at which martensite formation finishes during rapid cooling.
*Explain how Tensile Test is conducted. What property is studied and how?
Tensile Test Experiment
Introduction
One material property that is widely used and recognized is the strength of a material. But what
6. does the word “strength” mean? “Strength” can have many meanings, so let us take a closer look at
what is meant by the strength of a material. We will look at a very easy experiment that provides
lots of information about the strength or the mechanical behavior of a material, called the tensile
test.
The basic idea of a tensile test is to place a sample of a material between two fixtures called “grips”
which clamp the material. The material has known dimensions, like length and cross-sectional area.
We then begin to apply weight to the material gripped at one end while the other end is fixed. We
keep increasing the weight (often called the load or force) while at the same time measuring the
change in length of the sample.
Tensile Test
One can do a very simplified test at home.
If you have a way to hang one end of some material from a solid point that does not move, then you
can hang weights on the other end.
Measure the change in length while adding weight until the part begins to stretch and finally breaks.
The result of this test is a graph of load (amount of weight) versus displacement (amount it
stretched). Since the amount of weight needed to stretch the material depends on the size of the
material (and of course the properties of the material), comparison between materials can be very
challenging. The ability to make a proper comparison can be very important to someone designing
for structural applications where the material must withstand certain forces.
We need a way of directly being able to compare different materials, making the “strength” we
report independent of the size of the material. We can do that by simply dividing the load applied to
the material (the weight or force) by the initial cross-sectional area. We also divide the amount it
moves (displacement) by the initial length of the material. This creates what material scientists refer
to as engineering stress (load divided by the initial cross-sectional area) and engineering strain
(displacement divided by initial length). By looking at the engineering stress-strain response of a
material we can compare the strength of different materials, independently of their sizes.
To use the stress-strain response for designing structures, we can divide the load we want by the
engineering stress to determine the cross-sectional area needed to be able to hold that load. For
example, a 1/8” diameter 4340 steel wire can hold a small car. Again, it is not always that simple.
We need to understand the different meanings of “strength” or engineering stress.
Now it gets more complicated. Let us take a look at what is meant by the different strength values
and also look at other important properties we can get from this simple test. The easiest way is to
examine a graph of engineering stress versus engineering strain. Shown below is a graph of a tensile
test for a common steel threaded rod, providing a good example of a general metal tensile test. The
units of engineering stress are ksi, which stands for a thousand pounds per square inch. Note the
reference to area in the units. The units on strain are of course unitless, since we are dividing
distance by distance.
7. Graph Location 1: Elastic Region
Let us discuss some of the important areas of the graph. First, the point on the graph labeled number
1 indicates the end of the elastic region of the curve. Up to this point, the material stretches in an
elastic or reversible manner.
All materials are made up of a collection of atoms. Elasticity can be best understood by imaging the
atoms are connected by springs. As we pull on the material, the springs between the atoms get
longer and the material lengthens. The elastic portion of the curve is a straight line. A straight line
indicates that the material will go back to its original shape when the load is removed.
Graph Location 2: 0.2% Offset Yield Strength
The next portion of the curve of interest is point 2. At this point the curve has begun to bend over, or
is no longer linear. This point is known as the 0.2% offset yield strength. It indicates the strength of
the material just as it starts to permanently change shape. It is determined as the value of the stress
at which a line of the same slope as the initial portion (elastic region) of the curve that is offset by a
strain of 0.2% or a value of 0.002 strain intersects the curve.
In our example, the 0.2% offset yield strength is a 88 ksi.
This is a very important aspect of strength. It basically tells us the amount of stress we can apply
before the material starts to permanently change shape, putting it on a path to eventual failure.
Those who design parts that are used under stress must see that the stress or force on the part never
exceeds this value.
Graph Location 3: Maximum Withstand-able Stress
As we move up from point 2 the load or "stress" on the material increases until we reach a
maximum applied stress, while the material deforms or changes shape uniformly along the entire
gauge length. When we reach point 3, we can determine the tensile strength or maximum stress (or
load) the material can support. It is not a very useful property, since the material has permanently
deformed at this point. After we reach this point, the stress begins to curve drastically downward.
This corresponds to localized deformation, which is observed by a noticeable “necking” or
reduction in the diameter and corresponding cross-section of the sample within a very small region.
If we release the load in this area, the material will spring back a little but will still suffer a
permanent shape change.
Graph Location 4: Failure or Fracture
Finally, as we follow the curve we eventually reach a point where the material breaks or fails. Of
interest here is the final degree to which the material changes shape. This is the “ductility” of the
material. It is determined by the intersection of line number 4, having the same slope as the linear
portion of the curve, with the strain axis.
Our example shows a strain of 0.15. The 15% change in length is the amount of “ductility”.
When the sample fractures or breaks the load is released. Therefore, the atoms elastically stretched
8. will return to their non-loaded positions. Other information about the mechanical response of a
material can also be gathered from a fracture test.
Tensile Tests—Composites
If one pulls on a material until it breaks, one can find out lots of information about the various
strengths and mechanical behaviors of a material. In this virtual experiment we will examine the
tensile behavior of three different composite fiber materials. They have similar uses but very
different properties.
Procedure
A material is gripped at both ends by an apparatus, which slowly pulls lengthwise on the piece until
it fractures. The pulling force is called a load, which is plotted against the material length change, or
displacement. The load is converted to a stress value and the displacement is converted to a strain
value.
About the Materials
Testing materials are the composites fiberglass, Kevlar®, and carbon fiber. Composites are
combinations of two or more individual materials with the goal of producing a material having
unique properties not found in any single material.
All of these composites use epoxy as a matrix, which “glues” the fabric like arrangement of the
fibers of the respective materials.
Epoxies are thermosetting network polymers, which are very hard and strong, but on the brittle side.
All fabrics are of the same “weight,” which is a measure of fabric size or weight of a square yard.
An example of the fiber material made from fiberglass is shown above left. Kevlar is very similar
except it has a yellow color. The carbon has a black color. The samples used in this case are flat bars
cut out of larger material using a water jet saw. The three samples are shown below left.
Material Properties
Material Properties Fiberglass Kevlar® Carbon Fiber
Density P E E
Tensile Strength F G E
9. Compressive Strength G P E
Stiffness F G F
Fatigue Resistance G-E E G
Abrasion Resistance F E F
Sanding/Machining E P E
Conductivity P P E
Heat Resistance E F E
Moisture Resistance G F G
Resin Compatibility E F E
Cost E F P
P=Poor, G=Good, F=Fair, E=Excellent
Experiment
Final Data
Raw Data for Fiberglass
Corrected Data for Fiberglass
10. Corrected Data for Fiberglass
Corrected Data for Carbon Fiber
Conclusions
The carbon fiber composite material has a much higher tensile strength and modulus of elasticity
than the other materials. Note they all break in a “brittle” manner, as the curve is linear until it
breaks or fractures with no bending of the curve at high loads. Consequently, there is no permanent
change in original shape during this test, and hence no ductility.